1. Field of the Invention
Embodiments of the invention relate to blocked prepolymers. More specifically, embodiments of the invention relate to plastisol compositions comprising blocked prepolymers.
2. Description of the Related Art
Polyvinyl chloride (PVC) resins, suspensions, dispersions or emulsions are commonly dispersed in liquid plasticizers (with other additives) to form a plastisol. PVC-based plastisols have been widely used as an automotive and heavy machine chip-resistant undercoat, a body sealer, and an electrodeposition coating for wire-coating applications. However, PVC-based plastisols are alleged to present challenges to the environment and health. Recently, environmentally friendly plastisol formulations such as acrylic-based plastisol compositions have been accepted as substitutes for PVC-based plastisols by some automotive and heavy machinery manufacturers.
Acrylic-based plastisol compositions are thermoplastic and require heat and time for fusion. Thus, when the plastisol cures in a car production line, high temperatures of at least 130° C. are required to cure the plastisol into the undercoat membrane. Typically, curing the plastisol comprises preheating the plastisol for approximately ten minutes at 90° C. and curing the plastisol at 140° C. for approximately thirty minutes. Such high temperatures lead to both an increase in the energy required and a corresponding increase in the production time required.
Thus it is desirable to provide a lower temperature curing system to reduce both energy consumption and production time.